Tied Ridging Research Articles

Tied ridging enhances soil water conservation and productivity of common bean (<i>Phaseolus vulgaris</i>)

A field trial was conducted to determine the effects of different water conservation practices done in-situ on soil water content, stomatal conductance, and seed yield of common beans at Fumesua experimental station of the CSIR-Crops Research Institute in Ghana during the 2020 and 2021 cropping seasons. The water conservation practices implemented were tied ridges (TR), bunded basins (BB), and flat land (FL). Results showed that the TR treatment increased soil water content by 18 and 16% (0-5 cm), 12 and 13% (5-10 cm), and 18 and 7% (10-30 cm), compared with the FL treatment in 2020 and 2021 respectively. Across years, TR treatment increased stomatal conductance by 39 and 53% at both vegetative and flowering sampling periods. Soil water content and stomatal conductance also increased in the BB treatment compared to the FL treatment, but to a lesser extent than that of TR. The TR treatment improved seed yield by 31 and 42% over that of FL in 2020 and 2021, respectively. At a lesser magnitude, the BB treatment increased seed yield by 17 and 40% compared with the FL treatment during the same period. These results showed a positive relationship (p < 0.05) between the soil water content and common beans seed yield, such that an increase in soil water content determined about 75% of the increase in seed yield. Based on the results of this study, tied ridging could be considered a suitable water conservation strategy for improving common bean yield.

Impact of maize straw biochar and tied‐ridge‐furrow rainwater harvesting on soil erosion and soil quality in a semiarid region

AbstractIn dryland areas, integrating biochar soil amendment with in situ rainwater harvesting systems may decrease soil erosion, improve soil quality, and increase crop productivity and yield. This study was conducted to investigate the effect of maize straw biochar amendment and ridge‐furrow rainwater harvesting systems on run‐off, sediment yield and the physico‐chemical properties of a Calcic Cambisol soil in semiarid areas. The experiment was conducted on alfalfa (Medicago sativa) production land at the Anjiagou Catchment experimental station in Gansu province, China. The experimental layout was a split‐plot design with three replications. Biochar was applied at a rate of 0 and 30 t ha−1, respectively. The tillage treatments were flat planting, open‐ridging, and tied‐ridging (TR). Overall, the integration of maize straw biochar with TR decreased soil bulk density at 0–40 cm depth. Biochar application reduced run‐off by 37.8% and soil loss by 55.5% during alfalfa‐growing seasons compared to the control. In general, biochar addition increased soil total potassium, but the same effect was not observed for soil pH, total nitrogen, total phosphorus, and available phosphorus. These findings demonstrate the potential of integrating maize straw biochar and tillage systems to reduce soil erosion and improve soil quality for rainfed crop production in semiarid areas. Further studies on the effect of biochar‐tillage system interaction are warranted to improve soil conditions for plant growth and increase crop yield in dryland areas.

Evaluation of different rainwater harvesting techniques for improved maize productivity in semi‐arid regions of Zimbabwe with sandy soils

AbstractBackgroundMaize production in semi‐arid areas has been hindered by moisture stress and poor soil fertility. Long frequent droughts and shortening of growing seasons have been causing yield reduction. Limited knowledge of soil water management by farmers is another key contributor to poor maize yields in the smallholder sector. Therefore, the objective of the study was to investigate the effects of contour‐based and field‐based water harvesting technologies on maize grain yield and rainwater use efficiency under rain‐fed conditions on three farms (Jera, Kudzeeta and Manjengwa) with sandy soils in the Marange smallholder farming area of Zimbabwe. The experiment was laid out as a split plot in a randomised complete block design with three replications at each site. Contour‐based rainwater harvesting structures were the main treatments comprising tied contour (TC), standard contour (STDC) and infiltration pits (IP). Field‐based rainwater harvesting structures were the subplot treatments comprising tied ridges (TR), pot holing (PH) and the flat system (FLAT).ResultsResults showed that the contour‐based water harvesting structures significantly influenced (p < 0.05) maize grain yields. TCs had the highest maize grain yields compared with infiltration pits and STDCs over two cropping seasons. Maize yields on field‐based TR were significantly higher (p < 0.05) than on the FLAT but were not different (p > 0.05) with what was obtained on PH. The combination of TC and TR water harvesting technologies resulted in significantly higher maize yields (p < 0.05) than other combinations. TR and STDC also gave higher maize grain yield at Jera farm which was significantly different from other two farms. Rainwater use efficiency followed the same trend as maize grain yields, with TC having higher values but not significantly different (p > 0.05) from STDC.ConclusionIt can be concluded that farmers in semi‐arid areas adopt a combination of TC with either TR or PH to improve rainwater use efficiency and maize yields.

Effects of Ridge Tillage and Organic Manure Treatment on Growth, Leaf Nutrient Concentration and Pearl Millet (Pennisetum glaucum) Stover Yield in Semi-arid Northeast Nigeria

In the drier areas where crop production is often constrained by low and variable rainfall, the search continues for innovative practices in soil and crop management to make maximum use of the water available for crop growth. Field experiments were therefore conducted in the rainy season of the year 2020 at two locations with contrasting soil types (Sandy Loam), at Teaching and Research Farm of Faculty of Agriculture, University of Maiduguri (Unimaid) and Sandy Clay Loam texture at Alakaramti village both located within Maiduguri and its environs, in northeast Nigeria to evaluate the efficacy of ridging and manure amendment on improving the productivity of the millet crop. In each site, six (6) land preparation and manure treatments consisting of: flatbed (FB), open-ridge (OR), tied-ridge (TR), flat bed + manure (FBM), open-ridge + manure (ORM), and tied-ridge + manure (TRM) were laid out in randomized complete block design with four replicates. The results indicated that soil treated with organic manure irrespective of land preparation type or location had greater nutrient levels compared to the un-amended soil. Millet plants grown in FBM, ORM and TRM plots had increased plant height, number of tillers per plant and stem diameter irrespective of differences in soil type or time of measurement. Millet leaf N, P and K contents were all higher in the manure amended treatments than in the un-amended treatments irrespective of land preparation method or location. The spectacular growth performance exhibited by millet plants grown under manure amended treatments also translated in higher stover yields. Mean increases in straw yield relative to the FB treatment were 36.8% for FBM, 41.8% for ORM and 47.4% for TRM on the sandy loam soil. The corresponding increases in straw yield due to these treatments on the sandy clay loam soil were 116.7% for FBM, 81.1% for ORM and 146.7% for TRM. These results reinforce earlier findings that combining the land preparation practice of ridge tillage (RT) with application of animal manure such as cow dung has the potential of improving the productivity of the millet crop grown under the prevailing edapho-climatic conditions of Maiduguri in northeast Nigeria.

Soil Physical Properties and Root Growth of Pearl Millet as Affected by Ridge Tillage and Farmyard Manure

Ridge tillage (RT) and organic manure management are among promising agronomic practices for conserving soil moisture and improving soil physical environment in arid and semiarid rain-fed areas. The studies were conducted during the year 2020 farming season with two soil types from northeastern part of Nigeria to compare the relative efficacy of RT with and without organic manure in improving soil physical properties and root growth of millet under rain-fed semi-arid condition. The effects of the RT treatments in combination with organic manure were compared to the conventional flat-bed treatment (control, FB). The soil types chosen for the study were sandy loam soil located at the University of Maiduguri (Unimaid) and sandy clay loam located at Alakaramti village, respectively. The other land configuration and manure treatments compared were: open-ridge (OR), tied-ridge (TR), flat bed + manure (FBM), open-ridge + manure (ORM), and tied-ridge + manure (TRM) each laid out in randomized complete block design with four replicates. The combination of RT (open or tied) plus organic manure (ORM & TRM) performed better in terms of all measured parameters: bulk density (Bd), porosity (Tp), mean weight diameter (MWD), soil water content (SWC) and root growth as measured with root mass density (RMD) than the bare ridge-tilled (OR & TR) or flat bed with manure (FBM) and without manure (FB) treatments, irrespective of differences in soil type. The improvement in soil condition resulting from combining the practices of RT with organic manure application as reflected by reduced Bd, increased Tp, and higher profile SWC has enhanced millet root growth under the water limited rain-fed farming system of the study area. In regions like northeast Nigeria where low and variable rainfall often limits crop production, the practice of combining RT(open or tied) with organic matter input could be recommended as an optimal agronomic practice for improving drought resilience of crops like millet.

Influence of tied-ridge with biochar amendment on runoff, sediment losses, and alfalfa yield in northwestern China

BackgroundLoss of organic matter and mineral nutrients to soil erosion in rain-fed agriculture is a serious problem globally, especially in China’s Loess Plateau. As a result, increasing rainwater usage efficiency by tied-ridge-furrow rainwater harvesting with biochar is expected to improve agricultural productivity. Nonetheless, with limited knowledge on tied-ridge-furrow rainwater harvesting with biochar, small-scale farmers face the challenge of adoption, thus, the rationale for this study.Materials and methodsA field experiment was conducted to determine the influence of open-ridging (OR) and tied-ridging (TR) with bio-degradable film on ridges and biochar in furrows on runoff, sediment losses, soil moisture, fodder yield, and water use efficiency (WUE) on sloped land, using flat planting (FP) without ridges and furrows as control, during alfalfa-growing year (2020).ResultsRunoff in flat planting (30%), open ridging (45%), and tied ridging (52%) were decreased with biochar to the extent where sediment was decreased in flat planting (33%), open ridging (43%), and tied ridging (44%) as well. The mean runoff efficiency was lower in flat planting (31%), open ridging (45%), and tied ridging (50%) in biochar plots compared to no-biochar plots. In biochar and no-biochar plots, soil temperature on ridges of TR was higher than that on OR, which was higher than FP during alfalfa growing season. Soil temperature in furrows during alfalfa growing season in biochar and no-biochar plots were in the order FP > OR > TR. Mean soil water storage for FP, OR, and TR, in biochar plots was higher than in no-biochar plots. This indicates biochar has a beneficial impact on open riding. Total annual net fodder yield (NFY) was significantly (p = 0.00) higher in treatments in the order TR > OR > FP. Tied ridging had a significant effect on actual fodder yield (AFY) in biochar plots, while open ridging significantly affected AFY in no-biochar plots. Annual total mean NFY and AFY increased by 8% and 11% in biochar plots compared to no-biochar plots. In biochar and no-biochar plots, water use efficiency was in the order TR > OR > FP. Conclusively, water use efficiency was significantly higher (p = 0.01) in biochar plots compared to no-biochar plots.ConclusionWhen crop production is threatened by soil erosion and drought, mulched tied-ridge with biochar is beneficial to crop growth in rain-fed agriculture, according to this research. Smallholder farmers should be trained on applying this technique for water-saving to mitigate runoff, soil erosion, sediment losses, and improve food security in semiarid areas.

Soil nutrients and crop yield response to conservation-effective management practices in the sub-humid highlands agro-ecologies of Kenya

Crop productivity in most smallholder farming systems in Sub-Saharan Africa experience low use of soil amendment resources, low and erratic rainfall, frequent dry spells, and droughts. Rain-fed agriculture has a high crop yield potential if rainfall and soil nutrient input resources are utilized effectively. Thus, in 2011, we set up an on-farm experiment in Meru South (sub-humid) and Mbeere South (marginal sub-humid) sub-counties in upper Eastern Kenya to assess conservation-effective management (CEM) practices effects on maize (Zea Mays L.) yields response and soil nutrients. The CEM practices were; tied ridging (TR), mulching (MC), and minimum tillage (MT), with conventional tillage (CT) as a control. There were frequent dry spells and droughts during the experimental period. The experiment ran for four seasons, from the long rains season of 2011 (LR11), short rains seasons of 2011 (SR11), long rains season of 2012 (LR12), short rains 2012 (SR12), and long rains season of 2013 (LR13). In Meru South, TR and MT treatments had significantly higher phosphorus content (100% and 66%, respectively) than the control. Also, in the same site, Cu and Zn were high in MT than in CT treatments. In the Mbeere South site, the aboveground biomass yield was significantly higher in TR treatment (by 71%) than CT during SR11, while in LR12 season, it significantly increased by 72% and 46% under MC and TR treatments, respectively, than the control. The TR treatment had significantly higher aboveground biomass than the control (84% and 115%) in the SR12 and LR13 seasons. In Meru South, MC treatment had significantly higher aboveground biomass, which was significantly higher, by 39%, during the SR11 season and 46% in TR treatment in SR12 season than the control. This study highlighted tied ridging as the best-fit practice for enhancing maize crop aboveground biomass production in rain-fed farming systems of marginal lands and sub-humid regions receiving unreliable rainfall. Further, we recommend longer-term experimentation to explore CEM effects on soil nutrients.

Effects of Fertilizer Micro-dose and In Situ Rain Water Harvesting Technologies on Growth and Yield of Pearl Millet in a Semi-arid Environment

Declining soil fertility and low rainfall are key constraints to crop production and are threatening food security in semi-arid areas. Applying inorganic fertilizer at reduced amount (micro-dose) and in situ rainwater harvesting using infiltration pits (IP) or tied ridges (TR) are low-input strategies to cope with these constraints. This work investigates the effect of integrating fertilizer with in situ rainwater harvesting technologies on pearl millet growth, yield and household profitability among Tanzanian smallholder farming communities. Split plot field experiments were conducted from 2015 to 2017 cropping seasons. Flat cultivation (FC) with zero fertilizer application resulted in lowest grain yield ranging from 297 to 453 kg/ha and in a negative net profit (NP). The highest yield of 2202 kg/ha was obtained upon the use of recommended rate under IP, but it resulted in negative NP. Infiltration pits under 25% micro-dose resulted in relative higher grain yield (778–2202 kg/ha) compared to TR (887–1915 kg/ha) and FC (592–1144 kg/ha); despite higher yield, it resulted in negative NP. Tied ridges and FC with micro-dose at 25% of recommended rate had a yield advantage ranging from 537 to 959 kg/ha and 295 to 455 kg/ha, respectively, compared to farmer practices, and both resulted in positive NP. The use of micro-dose at 25% of recommended rate along with TR or FC which gave higher grain yield and NP compared to farmers practice is recommended to resource-poor farmers for improved pearl millet productivity.

Effect of runoff management and soil conservation practices on the growth and yield of Maize (Zea mays) in a sub-humid agro-climatic zone of Ile-Ife, Nigeria

Field experiments were conducted at the Teaching and Research Farms, Obafemi Awolowo University, Ile-Ife in a completely randomized design with five soil-water conservation (SWC) treatments: Contour bunds (CT); Infiltration pits (IP); Mulched plots (ML); Tied ridges (TR); and the Conventional practice (CP), which served as the control. Four (4) levels of soil moisture replenishment [50% (Full Replenishment), 25% (½), 12.5 % (¼), and 6.25 % (1/8)] after depletion to 50% of Field Capacity (FC) were considered as supplementary water application from an in-situ RWH system. Measurements of soil moisture in the soil profile, plant growth parameters and yield at harvest were made. Results showed that maize yield and WUE varied amongst the SWC practices and within the years from the experimental plots with substantial yield improvements. The TR and CT gave better yields compared with the ML and IP of the same year. The 50 and 25% replenishment levels under TR and CT also gave better yield and WUE compared with other levels of replenishment. Biomass yield for the 2008-2010 planting seasons recorded higher values in TR, IP and CT compare to the control experiment, while the moisture retention ability was better in TR and slightly lower in CT of the same year. In 2011 soil moisture replenishment, the 50% gave the highest yield in a TR, followed by the CT and ML treatments. The TR gave the best WUE for the 50% and in all cases the CP gave a comparatively low efficiency. The study concluded that the methods of soil moisture conservation practice is an effective way to increase water availability for higher crop yields; but a combination of the supplementary, in-situ RWH system could produce better results in terms of enhanced yield and mitigate against the adverse effect of short duration intra-seasonal drought.

The farm income and food security implications of adopting fertilizer micro-dosing and tied-ridge technologies under semi-arid environments in central Tanzania

Adopting fertilizer input and rainwater harvesting techniques play a significant role in minimizing soil nutrient deficiency and moisture stress impact, both prime causes of low crop productivity in Sub-Saharan Africa. This study analyses the extent to which fertilizer micro-dosing (MD) and tied-ridge (TR) technologies can improve smallholder farmers’ food security and farm income. A household survey data along with on-farm trial data collected from semi-arid Tanzania is used for the analysis. The trade-off analysis for multi-dimensional impact assessment model (TOA-MD) is applied for the income and food security impact assessment. The on-farm trial shows a yield increase ranging from 10 to 300 percent for millet, and between 60 and 400 percent for sunflower. The TOA-MD analysis shows that between 52 and 79 percent of farms could be positively influenced to adopt the technologies. The increase in mean net return per farm ranges between 186 and 305 PPP USD. Adoption of the technologies would decrease the percentage of food insecure farmers between 1.8 and 7.1 percent. The study concludes that the technologies have the potential to improve yield and farm income for many farmers. However, these technologies alone would not bring significant change in terms of reducing poverty and food insecurity.

English

Low use efficiencies of inorganic fertilizers coupled with their rising costs has diverted attention of farmers towards organic sources. A study was conducted in Yatta sub-county between October 2012 to February 2013 short rains and April-August 2013 long rainy seasons to evaluate how tillage, cropping and organic inputs influenced soil nutrient status. A randomized complete block design with a split-split plot arrangement replicated three times was used. The main plots were tillage practices (TP): Split-plots comprised the cropping systems (CS) while split-split plots were organic inputs, plus the control. The test crops were sorghum and sweet potatoes (Impomea batata) with Dolichos (Dolichos lablab) and chickpea (Cicer arietinum L.) added either as intercrops or in rotation. Soil was randomly sampled at 0 to 30 cm depth at the onset of the experiment and at maturity of test crop for NPK and % organic carbon (OC) analysis. Significant (P≤0.05) high level of K (1.91 Cmol/+kg), available P (51.45 ppm), total N (0.19%) and OC (2.19%), in combined TR, intercrop sorghum/chickpea with application of Minjingu rock phosphate (MRP)+ farmyard manure (FYM) during SRS of 2012 compared to the other treatment combinations was observed. Comparing different organic inputs, tillage practices and cropping systems combined tied ridges (TR), intercrop of sorghum/chickpea and MRP+FYM and FYM increased the soil nutrients status. Therefore, soil organic inputs such as MPR and FYM are viable alternatives to inorganic fertilizers for improving the soil nutrient status. The study therefore recommends incorporation of the organic inputs in combination with TR, as well as intercropping with legumes in their cropping systems to improve soil health and resilience. Key words: Cropping systems, tillage practices, organic inputs, semi-arid, soil nutrients.

Evaluating the Effects of In-situ Rainwater Harvesting Techniques on Soil Moisture Conservation and Grain Yield of Maize (Zea mays L.) in Fedis District, Eastern Hararghe, Ethiopia

In the drier farming regions of the world, where crop production is constrained by short growing period, unpredictable and short rainfall with sporadic run-off, in-situ rainwater harvesting is vital for successful crop production. In connection to this, a study was conducted in Fedis district of Oromia region during the main rainy seasons of 2015 and 2016 to evaluate the effects of in-situ rainwater harvesting techniques (Ridge Furrow (RF), Contour Ridge (CR), and Tied Ridge (TR)) on soil moisture conservation and grain yield of maize. A spilt-plot design was used and soil moisture content was measured at three growth stages of the crop to a depth of 60 cm with 20 cm interval. The results showed that water harvesting techniques significantly increased moisture conservation compared to the control, which was flat bed preparation. Averaged over the three stages, the TR, CR and RF treatments increased soil moisture storage by 134.59, 128.57, and 121.87%, respectively, compared to the control. The study also revealed that the in-situ rainwater harvesting techniques, due to the improved soil moisture storage, significantly affected grain yield of the maize. Averaged over the two years, the TR, CR, and FR increased the grain yield 143.14, 131.47 and 121.16%, respectively, over the control treatment. Therefore, in drier environments, such as Fedis, in-situ rainwater harvesting techniques can be recommended for better moisture conservation and subsequent improvement in crop production.

Minimum tillage, tied ridging and mulching for better maize yield and yield stability in the Central Highlands of Kenya

Most smallholder farmers in Sub-Saharan Africa and in Kenya have been experiencing a decrease in crop yields in the recent decades. Droughts and prolonged dry spells are common and water is becoming the main limiting factor during crop growing seasons threatening smallholder farmers’ livelihood. Hence, availability and adoption of conservation-effective management practices (CEM) that foster soil conservation, water retention, improved crop yield and yield stability under the small-holder rainfed farming system is desirable. Based on this, we evaluated effects of selected CEM techniques on maize (Zea mays L.) yields, yield stability and farmers’ willingness to take up the techniques. We hypothesized that, the CEM techniques will not only increase maize yield but also the yield stability. The selected CEM were minimum tillage (MT), mulching (MC) and tied ridging (TR) tested alongside a control (conventional tillage) (CT) in two sites, a semi-arid (with predominant soil type being Cambisols with cambic B horizons) and sub-humid agro-ecologies (with predominant soil type being Humic Nitisols), in the Central Highlands of Kenya. We implemented field trials on-farm for four seasons: short rains 2011 (SR11), long rains 2012 (LR12), short rains 2012 (SR12) and long rains 2013 (LR13). The test crop was Maize (Zea Mays L.). A key informant’s interview with the farmers who implemented the field trial was conducted to assess their willingness to take up CEM techniques. Rainfall distribution and amount varied widely between the two sites. Maize grain yields were significantly higher in TR and MC treatments during the LR12, SR12 and LR13 seasons in the semi-arid site compared to CT. Tied ridging doubled grain yields during SR12 season in the semi-arid site. In the sub-humid site, grain yields significantly increased under all the tested CEM techniques during SR11, LR12 and SR12 seasons. Maize grain yields were more stable under TR and MC with residual variances of 0.107 and 0.183Mgha−2, respectively in the semi-arid site. Mulching, MT and TR techniques indicated yield stability with residual variances of 0.017, 0.039 and 0.155Mgha−2, respectively, in the sub-humid site. We concluded that, under semi-arid conditions, tied ridging is a better CEM technique that not only positively affect maize yields but it also enhances yield stability. Under sub-humid agro-ecological conditions, mulching technique performed comparatively well in terms of increasing maize grain yields and yield stability. The n were further affirmed by the farmers’ willingness to continue practicing TR and MC practice in Mbeere South and Meru South, respectively.

Soil water storage, yield, water productivity and transpiration efficiency of soybeans (Glyxine max L.Merr) as affected by soil surface management in Ile-Ife, Nigeria

Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used. In this study, conventional (NC) and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-Ife, Nigeria. The conservation practices are: Tied ridge (TR), Soil bund (BD), Mulch (ML), Mulch plus Soil bund (MLBD), Tied ridge plus Mulch (TRML), Tied ridge plus Soil bund (TRBD). The practices were arranged in Randomised Complete Block Design with four replicates. Seasonal rainfall was 539 and 761mm in 2011 and 2012, respectively. Seasonal soil water storage (SWS) ranged from 485mm for NC to 517mm for TRML in the two seasons. ML increased the SWS in the upper 30cm of the soil by 17% while TR increased the soil water content in the lower 30–60cm by 22% compared with NC. ML reduced soil temperature in the upper 30cm between 2.2 and 2.9oC compared with NC, TR and TRML. Seasonal crop evapotranspiration ranged between 432mm for NC and 481mm for BD in the seasons. Grain yield increased by 41.7% and 44.3% for BD and MLBD, respectively compared with NC. Water conservation practices increased water productivity for grain yield by 14.0–41.8% compared with NC. Similarly, it increased average seasonal transpiration efficiency by 15.3–32.5% compared with NC. These findings demonstrate that when there are fluctuations in rainfall, in-situ water conservation practices improve SWS, land, and water productivity and transpiration efficiency of Soybeans.

Effects of selected soil and water conservation techniques on runoff, sediment yield and maize productivity under sub-humid and semi-arid conditions in Kenya

The aim of this work is to investigate the consequences of selected soil and water conservation techniques and tillage practices on runoff amounts, sediment yield and maize yields under semi-arid and sub-humid environments. Field trials were set in Kigogo primary school in Meru South Sub-County, Tharaka Nithi County, representing the sub-humid conditions, and Machang'a secondary in Mbeere South Sub-County, Embu County (semi-arid) in the central highlands of Kenya. The experiment layout was a randomized complete block design and the treatments were implemented in runoff plots. Tied ridging (TR) was the most efficient technique in reducing runoff and sediment yield and at the same time boosting crop yields in the semi-arid region. It significantly (p<0.05) reduced sediment yields by 94% compared to the conventional tillage (CT) during the study period. The effects were particularly strong in periods of below average rainfall (dry seasons). During the drier season of short rains 2010 (SR10), grain yield under TR was 7 times higher compared to CT (p<0.01). In the sub-humid region, minimum tillage (MT) generated high runoff but relatively low sediment yield compared to CT. During periods of enough rainfall (over 450mm per season) in the drier site, intercropping suppressed maize yields significantly (p<0.01) by 42% compared to conventional tillage in the drier site. The results on the magnitude of runoff and sediment under the different soil and farm management practices are crucial in selection and promotion of valid farm management practices and tillage alternatives that not only abate soil erosion but also boost agricultural productivity in both sub-humid and semi-arid agro-ecological zones.

English

Soil water conservation through tillage is widely accepted as one of the appropriate ways of addressing soil moisture constraints in rainfed agriculture. A field experiment was conducted for 6 seasons (2007 to 2009) to evaluate the effects of 3 tillage practices namely ox-plough (OP), subsoiling-ripping (SR) and tied-ridge (TR) on soil physical and hydro-physical properties of a sandy loam soil. Soil surface roughness, bulk density (BD), total porosity, crust strength, saturated hydraulic conductivity, steady infiltration rates and soil water storage were evaluated. Results showed that, mean inter-row BD (1.51 Mg m-3) and crust strength (3.05 MPa) with SR tillage were 7 and 15% greater (P &le; 0.05) than with OP, respectively. Inter-row infiltration rates for OP (7.9 cm h-1) were more than two fold greater than for SR (3.6 cm h-1) and TR (3.3 cm h-1). Soil surface roughness with TR was significantly greater than with OP and SR tillage systems. Soil water storage for TR (222 mm) exceeded (P &le; 0.05) that for OP and SR by 30 mm (16%) and 32 mm (17%), respectively. This study concluded that, ripping soil along planting line that are prone to surface crusting without disturbing the soil between crop rows was not effective as a conservation tillage method. Key words: Tillage, soil physical properties, soil water conservation, sandy loam soil, infiltration rate.

The Effect of Rainfall Characteristics and Tillage on Sheet Erosion and Maize Grain Yield in Semiarid Conditions and Granitic Sandy Soils of Zimbabwe

In semiarid regions, rainfall is one of the primary factors affecting soil erosion and crop production under rain-fed agriculture. The study sought to quantify the effect of rainfall characteristics on sheet erosion and maize grain yield under different tillage systems. It was carried out under semiarid conditions and infertile sandy soils of Zimbabwe. Rainfall amount and intensity were recorded every 24 hours, while sheet erosion was measured from four tillage systems (Conventional Tillage (CT), Mulch Ripping (MR), Tied Ridging (TR) and Bare Fallow (BF)). Maize (Zea mays L.) was grown on three tillage systems (CT, MR, and TR). Rainfall amount varied significantly (P&lt;0.001) between seasons (164–994 mm). CT recorded the highest average soil losses (15 t/ha), while MR and TR recorded 1.3 and 1.2 t/ha, respectively. Maize grain yields increased with increasing seasonal rainfall giving yield-responses of 0.9 t/ha (TR) to 1.3 t/ha (MR) for every 100 mm rainfall increment. Overall, treatments didnot differ significantly (P&lt;0.497), except during drier seasons (P&lt;0.025). Regression equations showed that yields can be confidently predicted using rainfall amount and time, withR2values of 0.82 to 0.94. Maize grain yields proved to be mostly dependent on rainfall amount than fertility. The productivity of the soils decreased with increased length of cultivation.

Yield and Water Use Efficiency of Millet as Affected by Land Configuration Treatments

ABSTRACT In the semi-arid areas of northeast Nigeria, which are characterized by low and variable rainfall, promising technologies for improving soil and water conservation are urgently needed. A 2-year field experiment was therefore initiated in 2000 to compare the relative efficacy of open ridge (OR), tied ridge (TR), pit planting (PP), and flat bed (FB) planting for increasing water conservation, yield, and water use efficiency (WUE) of millet in a sandy loam soil. Ridge heights were 15 to 20 cm, and furrows were left open for OR and tied for TR. Pits were about 10 cm deep and 20 cm wide with a half-circle bund created around them to guide run-off water into them. The treatments were laid out in a randomized block design with four replicates. Except at harvest time, soil water storage during other sampling dates was significantly (p < 0.05) higher with OR, TR, and PP than with FB treatment. Growth attributes (plant height and straw yield), grain yield, and WUE were all significantly greater with OR, TR, and PP compared with FB in both cropping seasons. Pooled across the experimental years, grain yield under OR, TR, and PP treatments exceeded that of FB by 23%, 35%, and 28%, respectively. The corresponding increases in WUE with these treatments, relative to FB were 23%, 33%, and 28%, respectively. Based on the conditions of this study, we concluded that TR and PP were more effective than OR for increasing millet yield and water use efficiency.

Improving water utilization in maize production through conservation tillage systems in semi-arid Zimbabwe

Soil erosion is rampant in Zimbabwe, especially in small-holder areas, which are characterized by highly erodible soils and low and erratic rainfall. Over utilization of land and poor ground cover, due to removal of crop residues after harvest, have perpetuated the problem and resulted in extensive land degradation. Conservation tillage systems have been developed to try and curb this problem; however, their effect on soil productivity has not been extensively studied. This study sought to quantify rainfall input in the soil, run-off, drainage and soil losses under different tillage systems. Research work was carried out in the semi-arid region of Zimbabwe under infertile granitic sandy soils. Soil erosion, run-off and drainage were quantified under three tillage systems, i.e. conventional tillage (CT), mulch ripping (MR) and tied ridging (TR), over three years. Growth-effective rainfall was computed from rainfall, run-off and drainage. Maize grain yields were also assessed across all treatments. Run-off and soil losses were significantly higher ( p < 0.001) under CT (104 mm y −1 and 34 t ha −1 y −1, respectively) compared to MR and TR (40 and 34 mm y −1 and 2 t ha −1 y −1, respectively). Significantly more drainage (by ∼12 mm) and growth-effective rainfall (by 52–58 mm) were recorded under MR and TR compared to CT ( p < 0.001), also implying a recharge of the ground-water under MR and TR. Overall yields did not differ significantly among the different treatments and only varied significantly during years with low and poorly distributed rainfall, in favour of the conservation tillage systems. Low yield variations across seasons were recorded under MR (2.2–3.9 t ha −1) and under TR (1.1–3.7 t ha −1), while CT had highly variable yields, from 0.9 to 4.6 t ha −1, depending on rainfall amount and pattern. Soil erosion can be effectively reduced, growth-effective rainfall increased and yields sustained if sustainable management systems are implemented. The productivity of the soils is thus maintained as high erosion rates are coupled with high nutrient losses and general degradation of the soil.

Assessing nutrient losses with soil erosion under different tillage systems and their implications on water quality

An increased public perception of the role of agriculture in non-point source pollution has stimulated the need for information on the effect of conventional and sustainable agricultural management systems on water quality. While information on run-off and soil erosion is readily available in Zimbabwe, there is dearth of knowledge on the relative losses of nutrients as a result of soil erosion and their effect on water quality. This study sought to quantify the amount of nutrients lost as a result of soil erosion and thus enable conclusions to be drawn on the implications on water quality. Research work was carried out in the semi-arid region of Zimbabwe under granite-derived, inherently infertile sandy soils. Soil erosion was quantified under three tillage systems conventional tillage (CT); mulch ripping (MR); tied ridging (TR) over three years. Run-off and sediments were analysed for N, P and K. The results showed that N and K losses were significantly higher ( p < 0.001) under CT (15.8 and 34.5 kg ha −1 yr −1, respectively) compared to the MR (2.3 and 0.6 kg ha −1 yr −1, respectively) and TR (2.7 and 4.3 kg ha −1 yr −1, respectively). Due to the immobility of P and its small quantities in these soils, P losses were also low across all treatments (<1 kg ha −1 yr −1), however CT had significantly higher losses ( p < 0.001). The study showed that CT results in high losses of nutrients, which would in turn reduce the quality of surface waters, due to high nutrient concentrations of especially, N, which stimulates the growth of algae and other aquatic weeds. The gravity of the situation would be higher, where soils are more fertile. MR and TR were efficient in reducing soil erosion and thus nutrient losses with run-off and sediments. Pollution of surface water sources can be greatly reduced if conservation tillage systems are used.